Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 1b4d3eec44b98773…

MALICIOUS

Office (OOXML) / .XLSX

189.1 KB Created: 2021-10-04 08:20:54 UTC Authoring application: Microsoft Excel 12.0000
MD5: 4e1166896d3974d70ab9e55d92c45f62 SHA-1: 36436bd941fc8cc2aacbb0b28e7b37b6977d852d SHA-256: 1b4d3eec44b98773cce4790155694bedef6bc80ff0cf9d27e076e026bf8ccbc0
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. While the macro content is truncated and heavily obfuscated, this technique is commonly used to download and execute secondary payloads. Without further deobfuscation or network analysis, the exact payload and delivery mechanism remain unclear.

Heuristics 1

  • Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
ed6c1fdac2ca183bac54299c7ffa054e950a2937049d42d25a429d706b9f25c8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 975714 bytes

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